GB2035641A

GB2035641A - Data transmission system

Info

Publication number: GB2035641A
Application number: GB7846320A
Authority: GB
Original assignee: ANGULA MENDOZA F
Current assignee: ANGULA MENDOZA F
Priority date: 1978-11-28
Filing date: 1978-11-28
Publication date: 1980-06-18

Abstract

A data transmission system has a master transceiver (10) and a plurality of subscriber transceivers (26) linked e.g. by radio telephone or land line. A device e.g. keyboard (18) allows the master unit (10) to call up a selected one of the subscriber units (26), which recognises its address (at 32, 34, 36) and sends a reply (40, 38) to which the master transceiver (10) responds by sending a signal which the subscriber unit (26) responds to (42) by sending (46, 38) information relating to a consumable (e.g. electricity, water, gas, cash etc., sensed at 44,45). The master unit includes a receiver (16), store (20), VDU (22), and an automatic typewriter and computing facility (24). <IMAGE>

Description

SPECIFICATION Data transmission system Field of the invention This invention concerns data transmission systems and is particularly applicable to the remote interrogation of facility metering devices such as electricity flow meters, gas meters, water meters and the like. It is to be understood however that the invention is not in any way limited to any of these particular applications and with suitable transducers can be applied to remote interrogation and monitoring of any remote functions such as parking meters, the use of bankers' cards and cheque cards and the like.

Background to the invention Hitherto monitoring of the use of facilities have involved the location of a metering device usually at the subscriber's premises which necessitates the regular reading of the device.

The present invention seeks to provide an alternative system which whilst allowing a record to be kept of the use of a facility or supply does not necessitate the regular routine meter reading to be performed.

In the case of applications in the field of parking meters and banker's cards and cheque cards etc. the invention will allow routine interrogation or arbitrary recording of the use of a facility according to a code allocated to the user so that the record of the use of the facility is maintained at a centralised location to allow subsequent charges for the use of the facility to be rendered to the user.

The invention According to the present invention a data transmission system comprises a master unit having at least a transmitter unit for transmitting an electrical signal coded with one of n different codes, a plurality of subscriber units each of which comprises a transmitter and a receiver, the receiver being adapted to receive the electrical signals from the transmitter of the master unit, decoding means for decoding the coded information, means for comparing the decoded information with information contained within a store, the information within the store corresponding to one only often possible codes so that only one of the comparison devices in the plurality of subscriber units is satisfied, the comparison unit which is satisfied producing a control signal which inter alia enables a transmitter within the subscriber unit and means within the master unit for transmitting instructions to the subscriber unit in which the transmitter unit has now been enabled to produce further control signals for interrogating at least one function monitoring device to cause information relating to the value of the function being monitored to be transmitted to the master unit which includes a receiver adapted to receive transmitted information from the transmitter of the subscriber unit and to temporarily store the received information and to decode same for processing and/or visual display.

Preferably the subscriber unit receiver includes two or more decoding devices which respond to differently coded electrical signals received by the subscriber unit receiver so that by transmitting appropriately coded information after the electrical signal coded with the said one of then possible codes which thereby select the subscriber unit which is to be interrogated, the coded electrical signals received by the subscriber unit receiver can selectively enable first one and then another function monitoring device and/or other circuits and/or devices.

Where the functioning monitoring device is for example an electric current flow meter, solenoid operated switch means (or any other electrically operable switch means) is conveniently provided in the supply line to the metering device and a control signal from one of the decoding devices responsive to signals received by the subscriber unit receiver is arranged to control the operation of the switching means so that if desired remote isolation of the supply can be effected either temporarily or on a more permanent basis. The same signals can switch on or switch off any external electrically controlled equipment which need have no relationship to the function being metered, e.g. security lights, enable/ disable alarms etc., up to a maximum of 12 in number.

Where the function monitoring device is a current consumption meter which is adapted to produce in coded electrical signals the total consumption of electrical energy according to some formula from some datum such as the date of installation of the meter then the signal received by the master unit receiver and the information decoded therefrom and placed into store will correspond to the total consumption of electricity by the subscriber concerned, since the previous reading. Therefore the price to be charged to the consumer can be evaluated. This may be evaluated by an arithmetical unit in the master, if included.The master unit may then provide a visual display of this information to allow an operator to prepare an account to be submitted to the subscriber or further logic functions may be provided for converting the net quantity of electricity consumed into a value to be billed to the subscriber and this may be displayed visually so that an operator can enter this amount on an account and address it to the subscriber concerned.In the alternative the information relating to the amount of electricity consumed and/or the cost of the commodity which has been consumed may be transmitted by way of coded electrical signals to an automatic typewriting device together with other information from the locations in the store which have been identified by the original code selected from then codes so that an account can be automatically prepared from the previously stored information and from the information obtained by interrogating the facility monitoring device in that particular subscriber unit.

Preferably the subscriber unit includes a memory containing information which can be presented as a coded electrical signal for transmission by the subscriber unit transmitter to be received by the master unit receiver in advance of any information from the subscriber unit transmitter to identify the source of the incoming information. Preferably the master unit includes a comparison stage for deter mining whether the answer-back information from the subscriber unit is that which is expected from the subscriber unit which has been identified by the selection ofthe code from then possible codes and only if this comparison indicates that the called-up subscriber unit is answering is the information from the subscriber unit which follows the initial coded signals processed by the master unit circuit.

The master unit typically will include a keyboard into which information can be punched or entered for example by pressing buttons numbered 0 to 9 to enable any one of a number of different codes each being represented by a unique number in the sequence 0 to 9999...(depending on the capacity of the coding etc.) to be selected.

In addition or alternatively the master unit includes a memory which has a plurality of locations in which coded electrical signals are stored and which can be addressed in turn in a cyclic manner so as to present to the transmitter in turn a series of electrical signals which will cause an appropriate sequence of coded electrical signals to be transmitted by the master unit transmitter so as to call up in turn the receiver unit and cause each facility monitoring device to be interrogated in turn and the information stored in the memory bank of the master unit updated and/or processed as previously described.

Itwill be appreciated that the invention is of particular application to the field of electricity supply monitoring and measuring and the compilation of consumer accounts to indicate the quantity of electricity consumed and the charge due to the electricity supply authority. However the invention may also be used to indicate volumes of any commodity such as gas or oil or water consumed by a user.

The application of the system to these other commodities can be readily effected by providing an appropriate transducer and the subscriber unit so that an appropriately coded electrical signal is obtainable corresponding to the flow rate or quantity of commodity which has passed the transducer.

In a modification of the system, subscriber units may take over the role of the primary initiating role and the master unit the relatively passive role. Here the subscriber units are associated with cheque card reading devices and/or similar monitoring units for producing coded electrical signals corresponding to the code on a cheque card or some other form of identity disc or the like and the information contained thereon is used to identify a location or series of locations in a large memory forming part of the master unit into which information can be fed and subsequently processed and if necessary stored in a similar or different form so as for example to provide instant access for a retail outlet or bank to the credit limit and if appropriate remaining cash drawing limit available for any particular customer tendering a cheque card or credit card.In the case of parking meters, cards or discs or other devices having unique coded information thereon may be issued to potential users of parking meters and provision made on the parking meters for reading the discs and transmitting appropriate information to the centralised master unit to indicate thereto the user and the length of time for which the user has used the parking lot so as to enter into a centralised memory the information and where appropriate the charge which the user must bear for using these facilities.

The invention will now be described by way of example with reference to the accompanying drawings.

List of figures Figure 1 is a block circuit diagram of an overall system, Figure 2 is a block circuit diagram of a transmitter and receiver unit suitable for location on a subscriber's premises to monitor the usage of electricity by the subscriber, Figure 3 is a block circuit diagram of the circuit block 1 of Figure 2 and Figure 4 is a block circuit diagram of the circuit block 2 of the block circuit diagram of Figure 2.

Detailed description of drawings Figure 1 illustrates a very basic system and is intended to illustrate the principie of the invention rather than any particular embodiment thereof.

As provided by the invention, a master unit 10 includes a transmitter 12 and aerial 14which is also selectively supplied by a receiver 16. The transmitter 12 can be supplied with coded information from a keyboard 18 to transmit a coded electrical signal and the receiver 16 includes decoding equipment for decoding received electrical signals and entering the information in a store 20. The latter can be displayed on a visual display unit (VDU) 22 and can also be outputted to an automatic typewriter or the like 24 adapted to process the information for compiling accounts etc.

The subscriber unit is denoted by reference numeral 26 and includes an aerial 28 and receiver 30 which is adapted to function permanently whilst the remainder of the circuit remains in a relatively quiescent state.

The output of the receiver is supplied to a first decoder 32so that coded information which produces a particular output in the decoder output 32 when compared in a comparator stage 34 will reveal an identity with programmed information in a store 36 preferably a programmable store and will produce in the output of the comparator 34 an output or control signal for turning on a transmitter 38.

Preferably a reply code source 40 is also enabled with the transmitter so that as soon as the receiver is energised, an answer-back or reply in the form of a coded signal is transmitted by the transmitter 38 and aerial 28 to be received by the receiver 16 (which is normally left operating continuously) so as to provide the master unit with a key to the fact that the subscriber unit 26 is in a position to transmit information to the master unit. By comparing the answer-back signal with the selected code entered on the keyboard 18so the master unit can be satisfied that the subscriber unit which it is desired to call up is in fact on line and if in fact the answer-back is incorrect the whole system can be cleared down and a further attempt made to contact the subscriber unit which is actually required.

Where this facility is provided the master unit transmitter is programmed to transmit a different level of information coded in a different manner as soon as the correct answer-back has been received and this different level of information will be received by the receiver 30 and be decoded by a second decoding device responsive only to the second level of information, the second decoding device being represented by reference numeral 42.

This second decoding device is normally quiescent but is rendered operable by the enabling signal from the comparator 34 and is arranged to produce a control signal for enabling a transducer 44 and signal coding device 46 for transmitting coded information to the transmitter 38. This coded information will relate to the output from the transducer 44 which in turn will relate to the usage factor or otherwise of the facility and will provide coded information to the receiver 16 which can be entered in the store 20 and/or displayed on the VDU 22 as required at the master unit.

Where additional information is required from additional transducers or from the one transducer operating in a different function or operating on a different facility third and fourth or more levels of coding may be applied to signals from the transmitter 12 and additional decoding circuits such as 42 etc. provided for providing additional control signals to additional circuits.

Preferably a circuit is provided for generating an end of message code for transmitting at the end of information transmission from the transmitter 38 so that the master unit is advised when all the required information has been transmitted from the subscriber unit and with the arrival of this signal the transmitter 12 in the master unit is arranged to transmit a clear-down signal which will be recognised by the subscriber unit as indicating that it can revert to its quiescent state in which only the receiver unit 30 and the part of the transducer concerned with recording information is operational.

A 4-digit display unit 45 (referred to as a customer display unit or CDU) may be added to the subscriber unit to enable the subscriber to view the number of units metered since the previous reading.

Figures 2 to 4 illustrate in more detail a complete subscriber unit for use with a master unit (not shown) and a description of the system incorporating the master unit and the subscriber unit shown in the drawings follows in particular in relation to the mode of operation of the system.

The numbers around the perimeter of the circuit box 1 and the numbers around the perimeter of circuit box 2 in Figure 2 are reproduced in Figures 3 and 4 to indicate the inputs and outputs in those circuits which relate to the numbered points in the circuit blocks 1 and 2.

This data transmission system is capable of demanding nine digits of information from any one of a possible 99,999,999 sub-stations (or an absolute maximum of 13,806,391,296. (If an 8-digit hexadecimal identification code is used). The information is organised in two groups of four plus a single decimal digit. The information is received on the second level, the first being taken up with the reception of an 8-digit identification check code (a ninth digit is possible to supplement the second level).

The master unit has five functions: 1. To select and "ENABLE" a single sub-station by sending an identification code.

2. To send address date demanding information from the sub-station, stored on the first information level (identification check, 8 digit).

3. To send address data demanding information from the sub-station, accumulated and stored at the second level (information proper, 8 digit).

4. To send a zero identification to disable the sub-station, and'shut down unncessary logic circuits and the sub-station's transmitter.

5. To store the information demanded from the sub-station, and to display and/or to code it to feed into other equipment.

1. An eight digit identification code is selected at the master unit and the START pulse received. This will reset all the counters and bi-stables on the MASTER LOGIC board and prime the logic for a complete demand sequence. When the START button is released the transmitter is switched on, and the clock oscillator will commence to send a train of pulses to the MASTER LOGIC board. These pulses are initially routed through the identification gate where they are divided by two, gated and combined so that further pulses last for two complete cycles (including the 1/2 clock period space between pulses).

The combined pulse is fed into a decade counter, where these pulses are counted, to get a sequential, 4-bit binary output. This 4-bit binary is fed into a binary to decimal decoder giving ten separate outputs, each of which is pulsed on once, one after the other in sequence. These outputs are designated "0" through to "9". The "0" output is not used, this gives a time delay equal to two clock pulses to allow the radio transmitter to settle down after switching on.

The "1" output opens a gate to allow the first 4-bit identication code digit to pass to four AF oscillators which modulate the transmitter. The binary address for this digit is also presented to a further four AF oscillators (not shown).

At the sub-station the binary address opens a binary store, and the first identification digit is loaded into the store. The binary address is decoded to decimal and is the "TRANSFER DATA" input to the store.

At the master logic board, as the gated pulses advance the counter, the remaining seven identification digits are transmitted to the sub-station in the same way, where they are loaded into the other seven binary stores in exactly the same way.

If each binary number loaded into store at the sub-station corresponds to a predetermined number, then an AND gate for each digit is opened as each correct digit is received. If all eight digits are correct, then eight inputs will be fed into an "8 Input NAND" gate, and the output will switch on all the rest of the sub-station logic and a radio transmitter to send any demanded information back to the master logic board in the master unit.

When all eight identification digits have been sent, the master will carry on the first function and give a ninth enable output which could be used to give a command to ancillary equipment at the sub-station.

When the ninth pulse finishes, a bistable latch closes the clock input gate to the identification coder and the first function is completed, and the second begins.

2. The clock pulses are now routed through a gate opened by the bistable latch, and they are divided, combined and counted in the same way as the first function. The binary output from the decade counter counting these pulses is cycling from "0" through to "9" in a 4-bit binary code. This binary code is fed to the four oscillators that were used to send the identification code digits. At the substation, the outputs from the four filters are fed to a binary to decimal decoder where the "1" to "9" outputs open the ident-check gates in turn. As they are selected, the preset binary information in the indent check stores, are fed in turn to four oscillators, the tones transmitted to the master unit, where they are directed to the display unit.The display unit also receives the binary address data of the ident check from the MASTER LOGIC unit so it knows which store to put the ident check information into.

When the master logic has cycled through the binary ident check address and the ninth digit address has ceased to be, then a bistable latch changes state and an output is sent to another AF oscillator to change the information store level at the sub-station, and a pulse is also sent to the display unit to inform it of the change of level. The second function is now completed and the third function begins.

3. The third function is a repeat of the second except that it takes place together with the level change pulse, so directing information from a different set of stores in the sub-station. The same MASTER LOGIC components are used to generate the sequential information address code.

However, when the ninth digit address has ceased to be, another bistable latch changes state and this closes the gate which allows the clock pulses to come into this stage. The third stage is now completed.

4. The fourth function begins when the latch that closed the gate for the second and third functions, opens another gate to recycle the first function; the ident coder, except that the ident is disabled so that all "O"s are sent and loaded into the ident stores at the sub-station.

"00000000" is not an ident code for any station so no sub-stations will respond, and the one we have just been "talking to" has now received an incorrect ident code, so it will switch its transmitter off, and run-down non-essential logic, so saving current. The fourth function is now completed.

5. During the second and third functions, the master received information from the sub-station, via radio. This was fed into the display unit along with address and level information from the MAS TER LOGIC unit. All the information was stored as it came in, so it is now available for display and'or interface to external equipment. This unit is equip pedfora 17-digit 7-segment display. Outputfrom the stores is multiplexed to cut down components, current consumption, and increase the life expectancy of the 7-segment LED displays (unless LCD is used).

On completion of the fourth function, a gate was opened to give a "READY" indication, and the transmitter was switched off. In spite of this, data in the display unit will be available until it is used to store further information from another sub-station.

The sub-station can store and send when requested, any binary information connected to it. But to achieve greater versatility, four decade counters are used to count and store pulses and few additional components are used to convert it into a 4-digit frequency counter. This frequency counter is used to count the output from an analogue to frequency converter, then it will perform the function of digital voltmeter, providing that the analogue to frequency converter has a range from 0 Hz to 9,999 Hz, and that the relationship between the input voltage and the analogue to frequency converter output frequency is linear.

Claims

1. A data transmission system comprising a master unit having at least a master transmitter unit for transmitting a coded electrical address signal, means for selecting the code from n different codes, a plurality of subscriber units each of which comprises a subscriber transmitter and a subscriber receiver, the latter being adapted to receive the electrical signals from the transmitter of the master unit, decoding means for decoding the coded information, means for comparing the decoded information with information contained within a store, the information within the store corresponding to one only of then possible codes so that only one of the comparison devices in the plurality of subscriber units is satisfied whereby only that one subscriber unit is called-up, the comparison unit which is satisfied producing a control signal which inter alia enables the subscriber transmitter (within that subscriber unit) and means within the master unit for transmitting instructions to the called-up subscriber unit to produce further control signals for interrogating at least one function monitoring device associated with that subscriber unit to cause information relating to the value of the function being monitored to be transmitted to the master unit, which latter includes a master receiver adapted to receive information from each called-up subscriber unit and storage means to temporarily store the received information from each subscriber unit, means for decoding same and means for processing and/or visual display of the information.

2. A data transmission system as claimed in claim 1 in which the subscriber unit receiver includes two or more decoding devices which respond to further coded electrical signals received by the subscriber unit receiver and the master transmitter is adapted to transmit further coded information after each address signal to selectively enable first one and then another function monitoring device and/or other circuits and/or devices in the called-up subscriber unit.

3. A data transmission system as claimed in claim 1 or 2 in which the functioning monitoring device is an electric current flow metering device.

4. A data transmission system as claimed in claim 3 in which the subscriber unit includes switch means in an electrical feed to the metering device which switch means can be operated in response to one or more of the said further coded electrical signals so that remote isolation of an electrical supply can be effected.

5. A data transmission system as claimed in claim 2 or 3 in which the subscriber unit includes switch means responsive to one or more of the said further coded electrical signals for controlling the operation of electrical equipment.

6. A data transmission system as claimed in any of claims 1 to 3 in which the function monitoring device is a current consumption meter which is adapted to produce a coded electrical information signal corresponding to total consumption of electrical energy (as seen by the meter) from a datum point to the present time.

7. A data transmission system as claimed in claim 6 further comprising computing means for computing from the information signals a value of the electricity consumes and further comprising automatic typewriting means responsive to the address signals and the information signals for typing therefrom a statement of account addressed to the consumer associated with the subscriber unit supplying the information signals.

8. A data transmission system as claimed in any of the preceeding claims in which the subscriber unit includes a memory containing information for transmission by the subscriber unit transmitter as an identity signal in advance of the transmission of any information by the subscriber unit transmitter, to identify the source of the subsequent information.

9. A data transmission system as claimed in claim 8 further comprising a comparison stage within the master unit for comparing the identifying signals with stored information, the comparison stage generating an acceptance signal only if the comparison .............is is satisfactory, so indicating that the called-up subscriber unit which is answering is the correct one called-up.

10. A data transmission system as claimed in any of claims 1 to 9 in which the master unit includes a keyboard by which information can be entered by pressing coded buttons to enable addresses to be entered.

11. A data transmission system as claimed in claim 10 in which the buttons are numbered 0 to 9.

12. A data transmission system as claimed in any of the preceeding claims in which the master unit includes a memory which has a plurality of locations in which coded electrical address signals are stored and which can be addressed in turn so as to present to the transmitter in sequence a series of electrical address signals so as to call up in turn each of a plurality of subscriber units.

13. A data transmission system as claimed in any of the preceeding claims in which the master unit includes a large memory in which information signals received from the subscriber unit is stored and updated.

14. A data transmission system as claimed in any of the preceeding claims in which the function monitoring device comprises a commodity measuring device such as a gas flow measuring meter or a water flow measuring meter.

15. A data transmission system comprising a master unit having a plurality of subscriber transmitter receiver units each having an input device, a master receiver/transmitter unit responsive to address signals transmitted by any one of the subscriber units in response to information relating to the address being entered in the input device thereof, a memory in the master unit containing at least one location for each of the subscriber units, the address signal identifying one of the memory locations, means for reading out of an addressed memory location any information stored therein for transmitting the read-out information via the master transmitter to the calling-up subscriber.

16. A data transmission system as claimed in claim 15 in which the input device is a keyboard, by which a number can be entered.

17. A data transmission system as claimed in claim 15 in which the input device is a card receiving slot and card reader for reading out from a card such as a Bank or Cheque or credit card, a number and or other information thereon.

18. A date tranmission system as claimed in claim 16 or 17 in which the information stored at each memory location is information relating to the credit rating of the holder of the card bearing the number allocated to that memory location.

19. A data transmission system as claimed in claim 16 or 17 in which the information stored at each memory location relates to the current state of the card holders Bank account or cash drawing facility or purchasing facility.

20. A data transmission system constructed arranged and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.